The refusal of blood transfusion by Jehovah's Witnesses in critical situations constitutes an ethical and juridical dilemma. The refusal to receive blood products by Jehovah's Witnesses is based on biblical verses. Recurring arguments to sustain this refusal regard the right to self-determination and the right to freedom of faith. If minors are involved, the problem is rendered even more difficult as the parental authority over young children needs to be taken into account. When adolescents are concerned, the situation if even more ambiguous since adolescents might be considered as mature enough to provide autonomous consent. On the basis of three cases, the most frequent bottlenecks that can come up in paediatric emergency services are highlighted : (1) the refusal of a blood transfusion by the parents of a young child; (2) the refusal by an adolescent and (3) prior refusal based on a "No Blood"-document. Regarding minors, the law on patients' rights in Belgium contains safety mechanisms concerning the preservation of physical integrity. Therefore, a key responsibility has been assigned to the physician. A step-by-step plan and a synoptic diagram are presented.